A wireless radiotelephone, such as a cellular telephone, typically operates in a wireless network by first registering its subscriber identity such as an international mobile subscriber identity (“IMSI”) and a mobile identity number (“MIN”), to the wireless network. Once registered, the cellular telephone is allowed to initiate and to receive a call in the network. In a normal mode of operation, the cellular telephone receives an incoming call by monitoring a page for the IMSI address, and accepting the incoming call if the IMSI of the page matches the IMSI of the cellular telephone. If the cellular telephone is not registered, the network may refuse a call initiated by the cellular telephone, and the cellular telephone will not be allowed to receive a call targeted to the cellular telephone. The cellular telephone may become unregistered in several ways. For example, the cellular telephone may no longer have a valid subscription with any wireless network; the cellular telephone may be in a locked mode where a user has failed to properly enter a passcode such as a personal identification number (“PIN”); the current visited network may not have roaming agreement with the subscriber's home network; or the cellular telephone may be missing a required user module such as a subscriber identification module (“SIM”) card for a Global System for Mobile Communications (“GSM”) type cellular telephone or a removable user identity module (“R-UIM”) for a code division multiple access (“CDMA”) type cellular telephone. For a SIM or R-UIM equipped cellular telephone, once the cellular telephone becomes unregistered and enters a locked mode, information contained in the SIM or R-UIM becomes inaccessible. However, an unregistered cellular telephone, or a cellular telephone in the locked mode, may still be operated in limited capability to initiate an emergency call to an emergency service center. The emergency call to the emergency service center may be identified by a prestored telephone number dedicated for emergency use, for example, 911 in the United States and 112 in Europe. However, the cellular telephone in the locked mode of operation is disallowed to receive any incoming call including a call back from the emergency service center.